Currently, a self-capacitive touch panel, with the advantages such as a simple structure, fast response, and high sensitivity, has become more and more widely used, especially in a portable mobile device, or at an occasion having strict requirements in volume of a device. In order to further reduce the size of the touch panel, in the prior art, a common electrode layer (COM layer) located in a touch operation area is usually divided into a plurality of small blocks to form touch electrodes.
FIG. 1 schematically shows the structure of a self-capacitance touch panel of an IPS liquid crystal display device in the prior art, and FIG. 2 schematically shows a solution for detecting defects in the self-capacitive touch panel of the prior art. In FIG. 1, reference numerals 11 and 12 respectively denote touch electrodes formed by division of a common electrode layer, and signal lines for connecting the touch electrodes and detection circuits. An insulation layer 13 is disposed between the touch electrodes 11 and the signal lines 12, and each of the touch electrodes 11 is electrically connected to a corresponding signal line 12 through a via hole 14 provided in the insulation layer 13. Since it is necessary to transmit a voltage signal Vcom of the common electrode to all the touch electrodes 11 through the signal lines 12 during display, the signal lines 12 generally pass through an entire touch operation area. In the touch panel having the above-described structure, a short circuit easily occurs between the signal line 12 and other touch electrodes 11 located at a same column as the touch electrode 11 connected to the signal line 12. This prevents a detection circuit from correctly recognizing a touch position and causes display abnormality. For example, as shown in FIG. 2, a signal line 12a is used for connecting a touch electrode all located in a first row and at a first column of a touch electrode matrix, and passes through other touch electrodes located at the first column. A short circuit is likely to occur between the signal line 12a and other touch electrodes than the electrode all.
FIG. 2 schematically shows a solution for detecting whether a shot-circuit defect exists between the signal line 12 and the touch electrode 11. Each odd-numbered-column signal line 12 is connected to a detection data line T1, and each even-numbered-column signal line 12 is connected to a detection data line T2. In practice, the touch electrodes 11 at odd-numbered rows of the touch electrode matrix are all connected to the detection data line T1, and the touch electrodes 11 on even-numbered rows of the touch electrode matrix are all connected to the detection data line T2. Switch elements are used to control turn-on and turn-off between the signal lines 12 and the detection data lines T1 and T2. It is possible to determine existence of a short-circuit defect based on pictures displayed by blocks corresponding to rows of touch electrodes, upon application of a detection signal to T1 and the T2, respectively. However, the above solution can be used to detect only a short circuit between all the odd-numbered rows and all the even-numbered rows, but cannot further determine a specific range in which the short-circuit defect exists.
To conclude the above, a new detection solution is in urgent need to solve the above problem.